This 18ft high oak monument erected in the grounds of a historic castle has become the butt of jokes on the internet - for closely resembling a TOILET PLUNGER. The Tree Charter Champion Pole was unveiled at Lincoln Castle on Monday (6/11) to help celebrate the 800th anniversary of the Charter of the Forest. The 18ft (5.4ms) high sculpture features a long oak 'handle' and a concrete plinth, making it look exactly like a huge loo plunger. Social media users took to Twitter to express their observations of the sculpture.